The project objectives are to develop a photodynamic treatment to render blood bank products free from envelope viruses including cytomegalovirus (CMV) and human immunodeficiency virus (HIV) and to kill malarial organisms and trypanosomes known to be transmitted via transfusion. A means to treat blood is essential because semlogic tests cannot identify all infected blood. Preliminary research in our laboratory has shown photodynamic killing of enveloped viruses (CMV, ERV, and others), malaria, and T. cruzi in free suspension as well as in whole blood and HIV within infected H9 cells. Tbe photoactive compound dihematoporphyrin ether (DHE) was activated in a flowing system using 630 mn light at 5 J/cm2. Initial tests for effects of the system on blood quality were also done as the proposed system must kill infectious agents without modification of essential blood elements. To further develop this photoactive system with DHE, a simian immunodeficiency virus andffl model will be used for infectivity testing including detection of provirus in cells by the polymemse chain reaction. Human and baboon blood will be used for other tests including RBC life span, platelet function, and pmtein integrity. A scaled up prototype system allows blood to be processed in 500 ml units. Additional toxicity and mutagenicity studies of DHE will be done. Although the DHE system will be fully developed, other photoactive dyes will be investigated in an effort to increase the efficiency of the photokilling system. The present system limits the light power that can be delivered because hemoglobin also absorbs at 630 nin. Preliminary tests here on other dyes that absorb at 700 nm (minimal hemoglobin absorption) and are more efficient at low light levels indicate that othcr dyes are worthy of intensive investigation. Collaborative arrangements have been established between our organic synthesis laboratory and three other university laboratories to develop new candidate dyes for antiviral screening and development. If these dyes prove advantageous over the existing system, they will be fully tested in the aninial model. The most efficient new dyes will follow the DHE test protocol. Our goal is the development of an efficient system for the inactivation of viral pathogens in free suspension and within ceus that also kills malaria and T. cruzi . The system should retain the integrity of all blood components, process a unit of blood in less than 10 minutes, and be adaptable for blood banks.